The generalized Kadanoff-Baym ansatz with initial correlations
Karlsson, D., van Leeuwen, R., Perfetto, E., & Stefanucci, G. (2018). The generalized Kadanoff-Baym ansatz with initial correlations. Physical Review B, 98 (11), 115148. doi:10.1103/PhysRevB.98.115148
Published inPhysical Review B
©2018 American Physical Society
Within the nonequilibrium Green’s function (NEGF) formalism, the generalized Kadanoff-Baym ansatz (GKBA) has stood out as a computationally cheap method to investigate the dynamics of interacting quantum systems driven out of equilibrium. Current implementations of the NEGF-GKBA, however, suffer from a drawback: real-time simulations require noncorrelated states as initial states. Consequently, initial correlations must be built up through an adiabatic switching of the interaction before turning on any external field, a procedure that can be numerically highly expensive. In this work, we extend the NEGF-GKBA to allow for correlated states as initial states. Our scheme makes it possible to efficiently separate the calculation of the initial state from the real-time simulation, thus paving the way for enlarging the class of systems and external drivings accessible by the already successful NEGF-GKBA. We demonstrate the accuracy of the method and its improved performance in a model donor-acceptor dyad driven out of equilibrium by an external laser pulse. ...